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BQ25703A: Critical register setting

Roy Chou1
Genius 16100 points
Part Number: BQ25703A
Other Parts Discussed in Thread: BQSTUDIO,

Hi team,

Could you let me know which register value is critical to set? (like 0x0B0A ; 0x0D/0C ....)

Condition : 

2S5P 18650 Lithium Ion

3.6A charging current

full battery voltage is 8.4V

external AC adapter is 12V/3A

Regards,

Roy

  • 0
    TI__Genius 10385 points

    Roy,

    Below are some suggested settings based on your criteria. In the future a good resource for this information is to use BQStudio to see what registers need to be configured and verify the configuration with section 8.6 of the datasheet.

    Charge Current Register: REG0x02: 0E00 (3584mA)

    Charge Voltage Register: REG0x04: 20D0 (8400mV)

    Input Current Register: REG0x0E: 3C00 (3000mA)

    ACOV is fixed, you may want to find out what the minimum voltage the adaptor can support before crashing is and configure the Input Voltage Register accordingly. Please refer to 8.3.9.2 of the datasheet for more details.

    I hope this helps!

    -Ricardo

  • 0 in reply to Ricardo
    TI__Genius 16100 points

    Hi Ricardo,

    We used 2S5P 18650 battery to test on BQ25703A charger EVB(PWR732A), here are some external power, battery, charger setting attributes.

     

    (1) Power supply provides 19V/2A to charger EVB VIN port.

    (2) Battery's full voltage is 8.4V and its capacity is 14500mAh.

    (3) Charger input current is set to 2A.

    (4) Charger input voltage is set to 19V.

    (5) Charger minimum system voltage is set to 6.144V.

    (6) Charger maximum charge voltage is set to 8.4V.

    (7) Charger charge current is set to 3.584A

     

    You can refer attached files for BQ25703A register dump of external adapter exists and not exists for the detail setting. Could you help comment below questions

    1. Why we always get 3.2V of 0B/0Ah register? We have set it to 19V but it can't work.

    2. What's CMPIN meaning? I check 2Ah register of CPMIN voltage is 0.42V.

    3. Does MOSFET mean a power switch to on/off power?

    4. Does BATDET operate in LDO mode mean that it provides power as much as battery have?

    5. How long will bit 1 or bit 2 be set in 21h register after plug in adapter? It seems to take about 100 ~ 200ms, right?

    6. We are not clear of section 8.6.5.1.

    7. Does AUTO_WAKEUP_EN bit 0 in 30h register be set usually? I mean it is set as usual not default on?

    8. Normally, does PROCHOT pin be used? Or is it enough to check CHG_OK pin only?

     

    Fullscreen 2S5P_with_charger.txt Download 
    [ 3106.736503] REG0x0 : 0x20e
[ 3106.736869] REG0x2 : 0xe00
[ 3106.737140] REG0x4 : 0x20d0
[ 3106.737419] REG0x6 : 0x0
[ 3106.737688] REG0x8 : 0x0
[ 3106.737960] REG0xa : 0x0
[ 3106.738248] REG0xc : 0x1400
[ 3106.738530] REG0xe : 0x2800
[ 3106.738810] REG0x20 : 0xa400
[ 3106.739088] REG0x22 : 0x0
[ 3106.739398] REG0x24 : 0x2800
[ 3106.739672] REG0x26 : 0xfe00
[ 3106.739946] REG0x28 : 0x3800
[ 3106.740225] REG0x2a : 0x2023
[ 3106.740515] REG0x2c : 0x5554
[ 3106.740807] REG0x2e : 0x7840
[ 3106.741083] REG0x30 : 0x210
[ 3106.741363] REG0x32 : 0x2b7
[ 3106.741637] REG0x34 : 0x0
[ 3106.741934] REG0x36 : 0x4a54
[ 3106.743092] REG0x38 : 0x8120
[ 3106.744341] REG0x3a : 0xa0ff
[ 3106.744737] battery charge current: 3584mA
[ 3106.745016] battery discharge current: 0mA
[ 3106.745285] VSYS volatge: 8320mV
[ 3106.745576] BAT volatge: 8256mV
[ 3106.745854] SET CHARGE_CURRENT: 3584mA
[ 3106.746128] MAX_CHARGE_VOLTAGE: 8400mV
[ 3106.746411] INPUT_VOLTAGE: 3200mV
[ 3106.746693] INPUT_CURRENT: 2000mA
[ 3106.746975] MIN_SYS_VOTAGE: 6144mV
[ 3106.751794] status:
[ 3106.751804] AC_STAT: 1
[ 3106.751810] ICO_DONE: 0
[ 3106.751816] IN_VINDPM: 0
[ 3106.751822] IN_IINDPM: 0
[ 3106.751828] IN_FCHRG: 1
[ 3106.751834] IN_PCHRG: 0
[ 3106.751840] IN_OTG: 0
[ 3106.751846] F_ACOV: 0
[ 3106.751852] F_BATOC: 0
[ 3106.751858] F_ACOC: 0
[ 3106.751864] SYSOVP_STAT: 0
[ 3106.751870] F_LATCHOFF: 0
[ 3106.751876] F_OTGOVP: 0
[ 3106.751882] F_OTGOCP: 0

    Fullscreen 2S5P_without_charger.txt Download 
    [ 2669.979461] REG0x0 : 0x20f
[ 2669.979898] REG0x2 : 0x0
[ 2669.980198] REG0x4 : 0x20d0
[ 2669.980499] REG0x6 : 0x0
[ 2669.980800] REG0x8 : 0x0
[ 2669.981104] REG0xa : 0x0
[ 2669.981402] REG0xc : 0x1400
[ 2669.981699] REG0xe : 0x0
[ 2669.982000] REG0x20 : 0x2000
[ 2669.982298] REG0x22 : 0x0
[ 2669.982596] REG0x24 : 0x0
[ 2669.982895] REG0x26 : 0x0
[ 2669.983255] REG0x28 : 0x6
[ 2669.983549] REG0x2a : 0x23
[ 2669.983842] REG0x2c : 0x3d3d
[ 2669.984133] REG0x2e : 0x7840
[ 2669.984428] REG0x30 : 0x210
[ 2669.984722] REG0x32 : 0x2b7
[ 2669.985019] REG0x34 : 0x0
[ 2669.985312] REG0x36 : 0x4a54
[ 2669.985605] REG0x38 : 0x8120
[ 2669.985898] REG0x3a : 0xa0ff
[ 2669.986194] battery charge current: 0mA
[ 2669.986490] battery discharge current: 1536mA
[ 2669.986783] VSYS volatge: 6784mV
[ 2669.987137] BAT volatge: 6784mV
[ 2669.987430] SET CHARGE_CURRENT: 0mA
[ 2669.987852] MAX_CHARGE_VOLTAGE: 8400mV
[ 2669.988183] INPUT_VOLTAGE: 3200mV
[ 2669.989072] INPUT_CURRENT: 0mA
[ 2669.989381] MIN_SYS_VOTAGE: 6144mV
[ 2669.993611] status:
[ 2669.993619] AC_STAT: 0
[ 2669.993625] ICO_DONE: 0
[ 2669.993632] IN_VINDPM: 0
[ 2669.993638] IN_IINDPM: 0
[ 2669.993644] IN_FCHRG: 0
[ 2669.993651] IN_PCHRG: 0
[ 2669.993657] IN_OTG: 0
[ 2669.993663] F_ACOV: 0
[ 2669.993669] F_BATOC: 0
[ 2669.993675] F_ACOC: 0
[ 2669.993682] SYSOVP_STAT: 0
[ 2669.993689] F_LATCHOFF: 0
[ 2669.993695] F_OTGOVP: 0
[ 2669.993700] F_OTGOCP: 0

    Thank you for your support.

    Regards,

    Roy

  • 0 in reply to Roy Chou1
    TI__Genius 16100 points

    Hi Ricardo,

    Any comments?

    Roy

  • 0 in reply to Roy Chou1
    TI__Mastermind 24075 points

    Hi Roy,

    1.    This is the VINDPM register. When input voltage hits this threshold, charger will regulate input voltage to this point, by decreasing charge current to reduce load on input supply. Default is 3.2V, so make sure you disable watchdog timer, so that it doesn't reset
    2. This is the input to the independent comparator, whose output will be on CMPOUT. If not using this pin, ground it and do not leave floating.
    3. I don't understand this question? Is customer asking what a MOSFET is?
    4. Is this referring to BATFET? LDO mode is active whenever the battery voltage (measured from SRN) is < the minimum system voltage (programmed in the MinSystemVoltage() register). In this mode VSYS is regulated to VSYSMIN setting
    5. Similar to CHRG_OK pin so should be 50ms deglitch timer after valid input. Section 8.3.2
    6. What specifically is unclear about this section? This section is describing operation of NVDC architecture which is pretty standard among our charger
    7. By default it is on to wakeup battery when adapter is plugged in. Meant for deeply discharged batteries and when adapter is disconnected. When re-connected this constitutes POR so default is on as we would like to safely wake up battery.
    8. PROCTHOT pulse is to be used to signal CPU to throttle power. If the platform power exceeds the available power from adapter and battery. 
      1. If not using charger in such a configuration then no need to use prochot.
      2. 8.3.8 shows when PROCHOT pulses are sent. If just needing adapter detection, you can use just the CHRG_OK pin.

  • 0 in reply to Kedar Manishankar
    TI__Genius 16100 points

    Hi Kedar,

    Thank you for your comments. I have discussion with customer and would like to some points with you.

     

    1.

    How long will bit 1 or bit 2 be set in 21h register after plug in adapter? It seems to take about 100 ~ 200ms, right?

    Similar to CHRG_OK pin so should be 50ms deglitch timer after valid input. (Section 8.3.2) – from you

    That is a conflict in our discussion. In our result in 0x21 register, sequence may be 0x21[7]=1 ; 0x21[2]=0 ; 0x21[1]=0 turn to 0x21[7]=1 ; 0x21[2]=1 ; 0x21[1]=0 or 0x21[7]=1 ; 0x21[2]=0 ; 0x21[1]=1. Duration is about 100ms~200ms and doesn’t sync to CHRG_OK bit. Is it right? 

    2.

    We are not sure the meaning of 30h bit 0 meaning

    If the battery is below minimum system voltage (REG0x0D/0C()), the device will automatically enable 128 mA charging current for 30 mins. When the battery is charged up above minimum system voltage, charge will terminate and the bit is reset to LOW.

    1st, if I always connect to adapter, is this condition occur?

    2nd,  if adapter is absent when battery is below minimum system voltage, and we connect an adapter in it. is the battery charge current = 128mA for 30min?

    3rd, honestly I dont know when will this condition occur?

    3.

    Which register could know the battery is fully charged(charge current = 0)

    Regards,

    Roy

  • 0 in reply to Roy Chou1
    TI__Genius 16100 points

    Hi Kedar,

    Any comments?

    Roy

  • 0 in reply to Roy Chou1
    TI__Mastermind 33075 points

    1. It takes 200ms for the device to start up and set the registers. 

    2. AUTO_WAKEUP_EN: When this bit is HIGH, if the battery is below minimum system voltage (REG0x0D/0C()), the device will automatically enable 128 mA charging current for 30 mins. When the battery is charged up above minimum system voltage, charge will terminate and the bit is reset to LOW.

    This happens when adapter plugs in, with a dead battery or no battery.

    3. Battery is considered full charged when the battery voltage reaches the max charge voltage (0x04) and charge current is below termination current (user setting).